Food-borne bacteria evolving, becoming more dangerous by Elizabeth Weise:
The evolution of ultra-dangerous versions of common food pathogens with which humans have coexisted for millennia. E. coli lives in the guts of most mammals. Almost all forms are harmless; some are actually necessary for health. It wasn’t until the 1970s that a deadly version — O157:H7 — emerged that causes kidney damage and death.
Two forms of the salmonella bacteria,Salmonella typhimurium and Salmonella newport, have evolved to resist most of the antibiotics that doctors are comfortable giving to children, says Patricia Griffin, who studies food-borne and diarrheal illnesses at the CDC.
Both are most common in cattle and other farm animals but are also turning up in fresh produce.